Receiver and tuner with electronically tuned filter

ABSTRACT

Tuners ( 2 ) comprising electronically tuned filters ( 22,24 ) like varicap tuned coil-capacitor tank circuits need to be electronically calibrated, without receivers ( 1 ) being near. To store calibration signals, said tuners ( 2 ) need memories, which do not go well with high-frequency technology. By providing tuners ( 2 ) with identifiers for identifying database fields in databases ( 40 ) situated outside receivers ( 1 ), calibration signals resulting from calibration processes can be downloaded for calibrating the electronically tuned filter ( 22,24 ) after installment in the receiver ( 1 ) and without the tuner ( 2 ) requiring any memory. Preferably, the receiver ( 1 ) comprises a receiver memory ( 11 ) located outside the tuner ( 2 ) for storing the calibration signal after downloading, and the database ( 40 ) is coupled to a network ( 41 ), like the internet or an intranet, with the receiver ( 1 ) comprising an in/output to be coupled to the network ( 41 ), and with the database ( 40 ) being a server. The tuner ( 2 ) comprises a digital-to-analog converter ( 27,28 ) for converting the digital calibration signal into an analog calibration signal.

The invention relates to a receiver comprising a tuner comprising atleast one electronically tuned filter. The invention also relates to atuner comprising at least one electronically tuned filter for use in areceiver comprising the tuner, to a method for electronically tuning atleast one electronically tuned filter in a tuner in a receiver, and to amethod of selling tuners.

Such a receiver is for example a television receiver, with the tuner forexample being a television tuner comprising an electronically tunedfilter like for example a varicap tuned coil-capacitor tank circuit.

A prior art receiver is known from EP 0 540 908 A1, which discloses inits FIG. 1 a receiver comprising a tuner having two electronically tunedfilters. The known receiver is disadvantageous, inter alia, due to notbeing manufacturer-friendly: tuners are usually manufactured separatelyfrom the receivers and by a first party and later installed in thereceivers by a second party. The first party should take care of thecalibrating (in other words: aligning), without receivers being near. Incase of the tuner for example being a television tuner, thehigh-frequency technology does not go well with semiconductor memorytechnology, and the tuner does not have a memory for storing calibrationsignals (alignment signals). Then the second party should do thecalibration process (alignment process), which is disadvantageous.

It is an object of the invention, inter alia, to provide a receiver asdefined in the preamble which is more manufacturer-friendly. Theinvention is defined by the independent claims. The dependent claimsdefine advantageous embodiments.

The receiver according to the invention is characterized in that thetuner comprises at least one identifier for identifying at least onedatabase field in a database situated outside the receiver for storingat least one calibration signal for calibrating the electronically tunedfilter.

By letting the first party do the calibration process and store thecalibration signal in the database field of the database, like forexample a laptop or a CD-ROM etc., the second party just needs to usethe identifier to be able to download the calibration signal from thedatabase field. This identifier for example comprises a number or abarcode etc.

The invention is based upon an insight, inter alia, that calibration ofelectronically tuned filters in tuners should be done directly aftermanufacturing and before installment of the tuners in the receivers, andis based upon a basic idea, inter alia, that calibration results do notneed to be kept inside/near the tuners.

The invention solves the problem, inter alia, of providing a moremanufacturer-friendly receiver, and is advantageous, inter alia, in thatthe manufacturing process has become more efficient. For example thehigh-frequency shielding encasing now no longer needs removable covers.Such removable covers were needed in the past to gain access to coilsduring the conventional tuner alignment procedure, in order to allowcoil inductance adjustments by mechanical deformation (opening/closingof coil windings).

A first embodiment of the receiver according to the invention as definedin claim 2 is advantageous in that the receiver comprises a receivermemory located outside the tuner for storing the calibration signal,with the tuner comprising a tuner bus coupled to the receiver memory forreceiving the calibration signal. By using the receiver memory forstoring the calibration signal, the downloading needs to be done onlyonce for each newly installed tuner.

A second embodiment of the receiver according to the invention asdefined in claim 3 is advantageous in that the database is coupled to anetwork, with the receiver comprising an in/output to be coupled to thenetwork. By introducing the network, like for example the internet or anintranet (in other words for example a PSTN/ISDN network+accessprovider+service provider), the database can be a server, with theidentifier for example comprising an Internet Protocol address or IPaddress and/or a Uniform Resource Locator or a URL, and thebefore-mentioned laptop and CD-ROM no longer need to be suppliedtogether with the tuner. Possibly, a small semiconductor memory islocated inside the tuner for storing the identifier. The in/output to becoupled to the network could for example further be used by clients forsurfing the web (thereby using the receiver comprising a network modemas a personal computer) and for downloading software and for sendingclient information to the second party or a third party etc.

A third embodiment of the receiver according to the invention as definedin claim 4 is advantageous in that the calibration signal stored in thedatabase and/or in the receiver memory is a digital calibration signal,with the receiver comprising a digital-to-analog converter forconverting the digital calibration signal into an analog calibrationsignal. By introducing the digital-to-analog converter, the calibrationsignals can be digitally stored and downloaded and the varicap tunedcoil-capacitor tank circuit can receive analog calibration signalnecessary for controlling this circuit.

A fourth embodiment of the receiver according to the invention asdefined in claim 5 is advantageous in that the tuner comprises thedigital-to-analog converter located between the tuner bus and theelectronically tuned filter. By locating the digital-to-analog converterin the tuner, the digital calibration signal is supplied to the tunerand there converted into analog format, thereby giving noise outside thetuner no chance to disturb the digital calibration signal.

Embodiments of the tuner according to the invention and of the methodaccording to the invention correspond with the embodiments of thereceiver according to the invention.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiments(s) described hereinafter.

The sole FIGURE illustrates in block diagram form a receiver accordingto the invention comprising a tuner according to the invention.

The receiver 1 shown in the FIGURE comprises a tuner 2, a processor (μP)10, a memory (MEM) 11, a demodulator (DEMOD) 14, a man-machine-interfaceor mmi 15, and a network modem 16 all coupled to a receiver bus 12,which is further coupled to an receiver in/output 13 which is coupled toa database 40 via a network 41. An input of demodulator 14 is coupled toan output of tuner 2, and an output of demodulator 14 is coupled to aninput of mmi 15 for example comprising a display or a screen,loudspeakers, an infrared interface for communication with a remotecontrol, a keyboard or keys etc.

Tuner 2 comprises an pre-amplifier (AMP1) 21 of which an input iscoupled to an antenna and of which an output is coupled to an input of afirst electronically tuned filter (ETF1) 22, of which an output iscoupled to an input of an further amplifier (AMP2) 23. An output of thefurther amplifier 23 is coupled to an input of a second electronicallytuned filter (ETF2) 24, of which an output is coupled to an input of amixer (MIX) 25. An output of mixer 25 is coupled to the input ofdemodulator 14, which further, for example, comprises yet furtheramplifiers, detectors, further filters, etc.

A control input of first electronically tuned filter 22 is coupled to anoutput of a first digital-to-analog converter 27 or A/D converter 27,and a control input of the second electronically tuned filter 24 iscoupled to an output of a second digital-to-analog converter 28 or A/Dconverter 28. A control input of mixer 25 is coupled to an output of anoscillator (OSC) 29 for example comprising a synthesizer, a Phase LockedLoop or PLL etc. Control in/outputs of pre-amplifier 21, of AD converter27, of further amplifier 23, of AD converter 28 and of oscillator 29 arecoupled to a tuner bus 30, which is further coupled to a tuner memory(TUN MEM) 26 and to a bus controller (CONT) 20 and to a tuner in/output31, which is further coupled to receiver bus 12.

The receiver 1 and the tuner 2 function as follows. Receiver 1 is forexample a television receiver, with tuner 2 for example being atelevision tuner comprising electronically tuned filters 22,24 like forexample varicap tuned coil-capacitor tank circuits.

Tuner 2 has been manufactured separately from receiver 1 by a firstparty (a tuner manufacturer) and has been calibrated by the first party,with the calibration signals (for calibrating electronically tunedfilters 22,24) however not being stored in tuner memory 26 due to tunermemory 26 either being too small for storing these calibration signalsor not being there at all (semiconductor memory technology does not gowell together with high-frequency technology). Later, tuner 2 isinstalled in receiver 1 by a second party (a receiver manufacturer).

According to a first possibility, the second party reads one or morenumbers present on/near tuner 2 and/or one or more barcodes presenton/near tuner 2, which numbers and/or barcodes are so-called identifiersfor identifying database fields in database 40 situated outside thereceiver 1. At these database fields, one or more calibration signalshave been stored by the first party for calibrating the electronicallytuned filters 22,24.

The second party for example connects a laptop to network 41 anddownloads the calibration signals from the database fields. Then, thecalibration signals are downloaded from laptop to receiver 1 viareceiver in/output 13 and stored in receiver memory 11 via receiver bus12 under control of processor 10. Then, whenever necessary, undercontrol of processor 10, the calibration signals can be supplied viareceiver bus 12 and tuner in/output 31 and tuner bus 30 to AD converters27,28 for example under control of bus controller 20, which ADconverters 27,28 convert the digital calibration signals into analogcalibration signals and supply the analog calibration signals to theelectronically tuned filters 22,24, which are now calibrated and whichcan now be used.

According to a second possibility, processor 10 decides that tuner 2must be calibrated, and reads via receiver bus 12 and tuner in/output 31and tuner bus 30 tuner memory 26 comprising an Internet Protocol addressor IP address and/or a Uniform Resource Locator or a URL being so-calledidentifiers for identifying database fields in database 40 situatedoutside the receiver 1. At these database fields, one or morecalibration signals have been stored by the first party for calibratingthe electronically tuned filters 22,24.

Then processor 10 makes a connection with database 40 via network 41 andvia receiver in/output 13, for example via network modem 16, withnetwork 41 for example being the internet or an intranet (in otherwords, for example, a PSTN/ISDN network+access provider+serviceprovider), and with the database for example being a server. Then, thecalibration signals are automatically downloaded from database 40 vianetwork 41 to receiver 1 via receiver in/output 13 and stored inreceiver memory 11 via receiver bus 12 under control of processor 10.Then, whenever necessary, under control of processor 10, the calibrationsignals can be supplied via receiver bus 12 and tuner in/output 31 andtuner bus 30 to AD converters 27,28 for example under control of buscontroller 20, which AD converters 27,28 convert the digital calibrationsignals into analog calibration signals and supply the analogcalibration signals to the electronically tuned filters 22,24, which arenow calibrated and which can now be used.

The invention is based upon an insight, inter alia, that calibration ofelectronically tuned filters 22,24 in tuners 2 should be done directlyafter manufacturing and before installment of the tuners 2 in thereceivers 1, and is based upon a basic idea, inter alia, thatcalibration results do not need to be kept inside/near the tuners 2.

The invention solves the problem, inter alia, of providing a moremanufacturer-friendly receiver 1, and is advantageous, inter alia, inthat the manufacturing process has become more efficient. For examplethe high-frequency shielding encasing now no longer needs removablecovers.

The receiver could further be an other kind of receiver like a car radioreceiver, and the input of pre-amplifier 21 could be coupled to anantenna, a cable, a satellite antenna etc. Tuner 2 could also be used ina receiver not comprising an extensive mmi 15, like for example aset-top-box. Tuner 2 will comprise at least one electronically tunedfilter or e.t. filter, but may comprise many more, up to hundreds ofthese e.t. filters. Then either each e.t. filter has its own identifier,or several e.t. filters share an identifier, with calibration signalscomprising indications which parts of the calibration signals aredestined for which e.t. filters. The content of tuner 2 is just anexample, there will be at least one e.t. filter, all other parts shownlike pre-amplifier 21, further amplifier 23, mixer 25 etc. may be thereor not. Instead of one DA converter per e.t. filter, there could be usedless DA converters in combination with a time multiplexing mechanismand/or analog buffers etc. Instead of pre-amplifier 21 being coupled tothe antenna, a (further) e.t. filter could be coupled to the antennaetc. More than one tuner could be located in the same encasing, likedefined in U.S. Pat. No. 6,151,488—“Multi-tuner receiver for concurrentreception of mutually different signals”. Each e.t. filter couldconstitute, inter alia, bandpass, lowpass, highpass and bandstop type offilters and is not limited to filters for RF signals but could alsoconstitute, inter alia, filters for IF signals or Base Band filters etc.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.The word “comprising” does not exclude the presence of elements or stepsother than those listed in a claim. The word “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.The invention can be implemented by means of hardware comprising severaldistinct elements, and by means of a suitably programmed computer. Inthe device claim enumerating several means, several of these means canbe embodied by one and the same item of hardware. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage.

1. Receiver comprising a tuner comprising at least one electronicallytuned filter, characterized in that said tuner comprises at least oneidentifier for identifying at least one database field in a databasesituated outside said receiver for storing at least one calibrationsignal for calibrating said electronically tuned filter.
 2. Receiveraccording to claim 1, characterized in that said receiver comprises areceiver memory located outside said tuner for storing said calibrationsignal, with said tuner comprising a tuner bus coupled to said receivermemory for receiving said calibration signal.
 3. Receiver according toclaim 2, characterized in that said database is coupled to a network,with said receiver comprising an in/output to be coupled to saidnetwork.
 4. Receiver according to claim 2, characterized in that saidcalibration signal stored in said database and/or in said receivermemory is a digital calibration signal, with said receiver comprising adigital-to-analog converter for converting the digital calibrationsignal into an analog calibration signal.
 5. Receiver according to claim4, characterized in that said tuner comprises said digital-to-analogconverter located between said tuner bus and said electronically tunedfilter.
 6. Tuner comprising at least one electronically tuned filter foruse in a receiver comprising said tuner, characterized in that saidtuner comprises at least one identifier for identifying at least onedatabase field in a database situated outside said receiver for storingat least one calibration signal for calibrating said electronicallytuned filter.
 7. Tuner according to claim 6, characterized in that saidtuner comprises a tuner bus to be coupled to a receiver memory forreceiving said calibration signal stored in said receiver memory. 8.Tuner according to claim 7, characterized in that said calibrationsignal stored in said database and/or in said receiver memory is adigital calibration signal, with said receiver comprising adigital-to-analog converter for converting the digital calibrationsignal into an analog calibration signal.
 9. Tuner according to claim 8,characterized in that said tuner comprises said digital-to-analogconverter located between said tuner bus and said electronically tunedfilter.
 10. Method for electronically tuning at least one electronicallytuned filter in a tuner in a receiver, characterized in that said methodcomprises the steps of identifying at least one database field in adatabase situated outside said receiver and of downloading at least onecalibration signal from said database field for calibrating saidelectronically tuned filter.
 11. A method of selling tuners, the methodcomprising: providing tuners that comprise at least one electronicallytunable filter and at least one identifier for identifying at least onedatabase field in a database situated outside said tuner; and operatingthe database that comprises the database fields for storing calibrationsignals for calibrating the electronically tunable filters.